Teacher seeking advice: Building a small EV (2 person tadpole trike with pedals) - Fuel Economy, Hypermiling, EcoModding News and Forum

Tander · 01-02-2012, 10:50 PM

Hello,

I am thinking about building a small EV with my students next semester and I am looking for some advice. I currently own and ride an electric bike but am thinking about something that one maybe two people could ride in. I teach Tech. Ed at a suburban high school so we have a pretty good fabrication facility. Im looking for technical advice. I am thinking about a three wheel vehicle (one rear drive wheel and two front steering wheels) with a pedal assist so it could qualify as a motorized bicycle. Questions I have - 1)Is a vehicle like this feasible? 2) How do I determine the size of motor needed? 3)How do I determine the amount of voltage and current needed to operate the motor? 4) What type of batteries are best suited for a vehicle like this? 5) What type of controls do I need for a project like this?

These are just a few questions to start with. I am sure that if I atttempt this project many more questions will follow.
Thank you,
Tander

MPaulHolmes · 01-03-2012, 09:51 AM

A fellow teacher!!! Absolutely something like that is feasible. Hub motors are pretty powerful these days. You could stick one of those in one or both front wheels. If you want it to move pretty well, I would do at least 36 volts, and at least 20 amps. Power is volts*amps, and you would probably need around 1 HP for 2 people, which is 746 watts. 36*20 = 720 watts. YOu could use a cheaper motor if you can get a gearing thing to work like with a belt or chain. Sealed Lead Acid batteries would probably be the easiest and cheapest way to go.

Two Sealed Lead Acid 12120 Rechargeable Scooter Batteries (2) - Nearly New | eBay

Lithium like "Headway" batteries would be better, but more expensive. Crap I have to go to school now to!

jamesqf · 01-03-2012, 01:20 PM

It's certainly something that can be done, and has been done. See here for some ideas: Twike - Wikipedia, the free encyclopedia

Ryland · 01-03-2012, 01:38 PM

I would go with one of the larger hub motors that can handle 72v so you can keep your wire size down, it will also keep your batteries happier.
Any idea on the goal for weight and speed?
Check out EVAlbum: Vehicle Types and Makes to see what others have done.